Botox Crossing the Blood Brain Barrier

Newsweek has published, in a somewhat sensational article, information from Italian researchers suggesting that Botox, when injected into mouse whisker muscles, was absorbed by the nerves at the injection site and passed on to other nerves. Within 3 days it had migrated to the brainstem where it disrupted neuronal activity.

There are several significant problems with this study. First of all the material that was used was not Botox, but a a laboratory made non-pharmaceutical preparation that is not suitable for human use. It is substantially different from the product used in humans, and it is quite clear that different preparations of the same botuinum toxin behave differently. The studies comparing Botox with the soon to be released Reloxin have made this evident.  Furthermore the dose of toxin used by the Italian researchers is, on a weight basis, 150 times the recommended dose of Botox that is approved to treat wrinkles.
There are anecdotal reports from physicians who administer large amounts of Botox that patients who have received Botox sometimes come in for Botox treatments citing some stressful event that has occured in their lives. In the June 2008 Journal of the American Academy of Dermatology there is an article that suggests that Botox treatment may enhance the mood of the patient.  One possible explanation is what has been called "facial feedback". By reducing frown lines, Botox treatment leaves the face looking more happy and less sad or angry. This more positive facial appearance leads to an internal experience of happiness in the individual. Also, the happier expression elicits happier responses from others, reinforcing the happy state of the  treated individual.
The opposite may also be true. Because unhappy expressions are blunted, unpleasant  life experiences  may not be reinforced by  equally  negative facial expressions.
Currently the evidence for a negative effect of Botox on the central nervous system is very weak. The  data that currently exists, while far from perfect, suggests that just the opposite is true.

Gerald N. bock MD
California Skin & Laser Center
Stockton &  Lodi, CA